Friction grip for drilling machines



Oct. 11, A HOSSFELD FRICTION GRIP FOR DRILLING MACHINES Filed Jan. 25, 1932 spaced to form main leaves 19. The outer end portions of the main leaves 19 are also U-shaped and formed by folding said leaves outward upon themselves and spacing the same laterally to form a pair of auxiliary spring leaves .20. These auxiliary leaves are relatively-short with respect to the main leaves 19 and said main leaves close to the free ends of said auxiliary leaves arebent 7 a varyingdiameter at different longitudinallaterally outward to form a pair of saddles 21 that are substantially semi-circular in cross-section and in opposing relation. The axes of the saddles 21 are parallel to the axis of the drill body 7 and are fitted circumferentially around said body at diametrically opposite ,sides thereof. The concave sur fl faces of the saddles 21 have the same contour or, in other words, the same diameter or approxlmatelythe same diameter as said body for frictional' contact ,with the drill body 7 throughout substantially its entire circumference.

The main leaves 19 are drawn toward'each other to frictionally press the saddles 21 onto the 'drillbody 7 under a pressure that may .be varied, at will, by a nut-equipped. bolt 22.. This draw bolt v22 extends through aligned holes inthemain leaves 19 and the auxiliaryleaves 20 and which holes are rela tively close to the free end portions of the auxiliary leaves and to the saddles 21. The head of thezbolt 22 engages the outer face of one of the auxiliary'leaves 20 and the nut on said bolt engages theouter face of the other of saidauxiliary leaves. It will be noted that the holes in the main leaves 19 t irough which j the bolt 22 extends are somewhat larger than the diameter of said bolt to permit angular movements of the main leaves 19 with respect to said bolt. 1 a e The-body of the bolt 22 adjacent to its head is square incross-section and is fitted in a like hole in theadj acent auxiliary leaf 20 to preventsaid bolt fromturning about its longitudinal axis during the :turning of the nut thereon, Before the nut'is turned onto the bolt 22 sufficiently to spring-the leaves 19 and 20 the main-leaves 19 are substantially parallel to each other and the auxiliary leaves 20 are also parallel to each other and to .the

nmain leaves .19, see Fig. 3.

crease the frictional contact between the sad- .dles 21 and-the drill body 7, the auxiliary When turning the nut on the bolt 2 2, to inleaves 20 always remain parallel to each other due in part to the distance the bolt 22 at :its axis is spaced from the connected ends of the auxiliary leaves 20, as indicated by. 7 broken lines X in Fig. 4.

1 While the adjustment of the grip 14 to increase its frictional contact with the drill body 7 does not move its auxiliary leaves 20 out of parallel arrangement with each other said saddles.

into positions in which they converge in opposite directions from said axis,.as shown by broken lines Y in Fig. 4. This springing of the main leaves 19, however, does not change the contour of the saddles 21 so that they always have a constant frictional engagement with the drill body 7 throughout their entire circumference. j p

In case the drill body 7 wears, so that it has ly spacedpointsthereon, the friction grip 14 will automatically adjust itself thereto and the frictional contact between the saddles 21 and the drill body-7 may be varied, at will,

responds to thesteps of movement of the drill 5. as its cutter 6-wears or cuts away the rock or other materialin which. a hole is being drilled. It will thus be seen that the frictionalj contact between the grip14 and the drill body 7 must be sufiicient tohold the grip 14 from moving on the drill body 7 under the action of the springs 15 and 16 but atthe same time must not interfere with the automatic -feeding of the drill 'body 7 therethrough. 7 V

The co-action of the leaves 19 and 20 of the grip is such as to produce therequired frictional contact between the saddles 21'and the drill body 7 -which is substantially the same over the entire frictional surfaces of This even contact between the saddles 21 and the drill body 7 not only produces a maximum amount of friction therebetween but produces an even wear between the saddles 21' and the drill body 7 and-hence reduces wear to a minimum. a 1 7 What l'claim is:

' '1. A friction grip comprising a U-shaped resllientmember, a pairof auxiliary spring members on the main leaves of said member and overlapping the same, said main leaves :having a pair of half seats "in their opposing "faces and intermediate of their ends, and means operative on the auxiliary spring 1 'member to press themain'leaves toward each other.

2. A, friction grip comprising a U-shaped resilient member, the main leaves of which are foldedoutward upon themselves and laterally spaced to afiord a pair of auxiliary leaves which, together with the connected portions of the main leaves, are also U- vshaped, the space between the auxiliary leaves being open and unobstructed, and

means operative on the auxiliary leaves to press the main leaves toward each other.

3. A friction grip comprising a U-shaped resilient member, the main leaves of which are folded outward upon themselves and laterally spaced to afford a pair of auxiliary leaves which, together with the connected portions of the main leaves, are also U- Y shaped, the space between the auxiliary leaves being open and unobstructed, and a nut-equipped bolt extending through aligned holes in the main and auxiliary leaves with its head and nut held by the auxiliary leaves 7 as basis of resistance and operable when the nut is turned inward thereon to press the main leaves toward each other.

4. The structure defined in claim 3 in which the holes in the main leaves are larger than the diameter of the bolt to permit angular movements of the main leaves with re spect to the bolt.

5. The structure defined in claim 2 in which the main leaves have in their opposing faces saddles.

6. The structure defined in claim 2 in which themain leaves have in their opposing faces substantially semi-circular saddles that extend axially transversely thereof.

7. The, structure defined in claim 2 in which the main leaves have in their opposing faces saddles that extend transversely thereof and in which the free ends of the auxiliary leaves terminate close to the saddles and the bolt is relatively close to said ends of said auxiliary leaves.

In testimony whereof I affix my signature.

ALBERT HOSSFELD. 

